1. Field of the Invention
This invention relates generally to a filter conditioning apparatus, and more particularly to providing a structure and method for enhanced pretreatment of a filter used with lithographic compositions prior to process application.
2. Description of the Background
The continued miniaturization of circuit features in semiconductor manufacturing has led to increased demand for finer and smaller lithographic features. Finer lithographic features require a well defined and defect free application of anti-reflective coating materials and compounds, such as photoresists. It has been determined that for acceptable semiconductor device yields employing finer lithographically produced circuit features, proper filter conditioning and filtration of photoresists combined with optimized application pumps are required. The continued evolution to finer pore sizes used in resist filters has led to difficulties in filter wetting, and the expulsion of air out of the filter media. If air has not been completely removed from the filter, the air will gradually be introduced into the compounds and photoresists that pass through the filter, thereby introducing air pockets or bubbles into the compounds. The bubbles result in defects in the applied compounds and resists that may have an adverse affect on semiconductor formation and performance. The potential resultant defects include image distortion at expose, breakthrough during reactive ion etching (RIE) processing, open line or trace defects. In addition, particle generation can occur if the bubbles burst during processing or use.
The present practice employed to precondition filters, employed in a lithographic process, is to continuously wet the filter until the expulsion of air out of the filter is complete. The photoresist solution used to precondition the filter is continuously dispensed to a drain or a waste receptacle. The venting and purging process to completely flush residual air from the filter can take from a couple of hours to a couple of days to complete. The present filter conditioning process is an expensive, waste generating, and time consuming process.